This application is directed to epoxy resin coatings of improved properties. Epoxy coatings possess many properties that make them desirable for use as a coating material, particularly as a coating material for steel. For example, they adhere well to steel, have good application properties and are readily available. Epoxy coatings also have good chemical resistance to many chemicals and solvents. However, the resistance of epoxy resins to attack by some solvents, such as acetone and methanol, can be poor. The properties of an epoxy resin film depend upon the chemical nature of the cure linkage, extent of cross-linking relative to chain extension, and cross-linked density. The most important commercial cure mechanisms use aliphatic amines, aromatic amines, and carboxylic derivatives. Unfortunately, the amines and carboxylic derivatives result in cured materials which are generally sensitive to acid or hydrolytic degradation. A structural basis for the susceptibility degradation, when using an amine curing agent, is the presence of the substituted nitrogen group in the matrix which can be protonated by acid and undergo a series of degradation reactions. In the case of cure with carboxylic acid derivative, an ester linkage results. Ester groups are subject to hydrolysis catalyzed by both acid and base.
In summary, acid and hydrolytic resistance is a problem experienced in the use of epoxy resins.